Deck 13: Competition

Question 1

During droughts in the Galápagos Islands, the ground finches most likely to survive are those with

A) smaller bodies.
B) smaller bills.
C) earlier maturation.
D) larger bills.
E) larger territories.

Answer 1

D

Question 2

In the Lotka-Volterra competition equations, if α₂₁ > 1, then

A) the population growth rate of species 2 is reduced equally by individuals of either species 1 or species 2.
B) the population growth rate of species 2 is reduced more by each individual of species 2 than by each individual of species 1.
C) the population growth rate of species 2 is reduced more by each individual of species 1 than by each individual of species 2.
D) We would also have to know the value of K₂ to decide which of the above is true.
E) We cannot tell from the parameters of the equation which of the choices is true.

Answer 2

C

Question 3

In the Lotka-Volterra competition equations, the parameter α₁₂ relates to the

A) population growth rate.
B) carrying capacity in the absence of competition.
C) carrying capacity in the presence of competition.
D) effect OF species 2 ON population growth rate OF species 1.
E) effect OF species 1 ON population growth rate OF species 2.

Answer 3

D

Question 4

Joseph Connell discovered that Balanus barnacles were excluded from the upper intertidal zone by ________, while Chthalamus barnacles were excluded from the middle intertidal zone by ________.

A) competition from mussels; prolonged immersion in water
B) competition from mussels; competition with Balanus
C) prolonged exposure to air; competition with Balanus
D) prolonged exposure to air; competition with algae
E) predation by wading birds; predation by starfish

Question 5

In mature white pine forests of New Hampshire

A) belowground interspecific competition suppresses the growth of herbaceous plants and hemlocks.
B) belowground interspecific competition suppresses the growth of white pine seedlings.
C) aboveground intraspecific competition suppresses the growth of white pine seedlings.
D) aboveground interspecific competition suppresses the growth of herbaceous plants and hemlocks.
E) belowground intraspecific competition suppresses the growth of herbaceous plants and hemlocks.

Question 6

Self-thinning in a stand of trees

A) increases biomass per individual.
B) decreases stand density.
C) results in death of less competitive individuals.
D) is a result of intraspecific competition.
E) All of the choices are correct.

Question 7

Gause's laboratory experiments with Paramecium species provided evidence for

A) character displacement.
B) the niche.
C) self-thinning rule.
D) competitive exclusion principle.
E) All of the choices are correct.

Question 8

Which of the following is not included in the list of criteria that Taper and Case believe must be met to build a definitive case for character displacement?

A) Morphological differences between a pair of sympatric species are statistically greater than the differences between allopatric populations of the same species.
B) The observed differences between sympatric and allopatric populations have a genetic basis.
C) Variation in the character must have a known effect on the use of resources.
D) There must be demonstrated competition for the resource under question and competition must be directly correlated with similarity in the character.
E) All of the choices are included in the list of criteria that must be met to build a definitive case for character displacement.

Question 9

In plants, "self-thinning" refers to reduction in

A) the biomass of an individual in response to competition.
B) the total biomass of a population in response to competition.
C) both population density and population biomass in response to competition.
D) population density in response to competition, as population biomass increases.
E) population density due to grazing by herbivores.

Question 10

In Thomas Park's experiments with Tribolium beetles, which of the following was true?

A) T. confusum and T. castaneum had identical niches.
B) T. confusum and T. castaneum always coexisted when cultured together.
C) T. confusum and T. castaneum never coexisted when cultured together.
D) T. confusum and T. castaneum could coexist under some environmental conditions, but not all.
E) T. confusum and T. castaneum proved to be unsuitable species for laboratory experimentation.

Question 11

If the isocline for species 1 lies above that of species 2,

A) species 2 will eventually exclude species 1.
B) a stable coexistence of the two species has been established.
C) species 1 will eventually exclude species 2.
D) an unstable coexistence of the two species has been established.
E) all growth trajectories lead to the point where N₂=K₂ and N₁=0.

Question 12

Analysis of the Lotka-Volterra competition model implies that two competitors can coexist only when

A) interspecific competition is stronger than intraspecific competition.
B) intraspecific competition is stronger than interspecific competition.
C) intraspecific and interspecific competition are equally strong.
D) predation or parasitism is stronger than interspecific competition.
E) Actually, the model implies that two competitors can never coexist.

Question 13

Intraspecific competition among planthoppers

A) results in reduced survivorship.
B) results in increased development time.
C) occurs via resources rather than interference.
D) occurs because plants exploited by planthoppers have less protein and less moisture.
E) All of the choices are correct.

Question 14

Two species occurring together in the same place are said to be

A) competitors.
B) precocial.
C) mutualists.
D) allopatric.
E) sympatric.

Question 15

Competition between members of a single species is called

A) cohort specific competition.
B) species specific competition.
C) interspecific competition.
D) intraspecific competition.
E) interference competition.

Question 16

Which of the following does NOT contribute to determining the niche of the salt-marsh grass Spartina anglica?

A) The height of tidal fluctuations
B) The fetch of the estuary
C) Latitude
D) Temperature
E) Rainfall frequency

Question 17

Which of the following statements about damselfish on Jamaican reefs is false?

A) Damselfish engage in both intraspecific and interspecific competition.
B) Damselfish compete for territories they use for feeding.
C) Damselfish attack intruders threatening their young.
D) Damselfish without territories die.
E) Competition in damselfish is "interference" competition.

Question 18

When the average mass of individual plants in a stand is plotted against stand density (log-transformed), the slope of the relationship is very often around

A) -1/2.
B) -1.
C) -3/2.
D) +1/2.
E) +3/2.

Question 19

Gause's "competitive exclusion principle" states that

A) when two species occur together, competition is always prevented by some behavioral adjustment.
B) no two species can coexist indefinitely.
C) no two competing species can coexist indefinitely.
D) no two species with identical niches can coexist indefinitely.
E) None of the choices are correct.

Question 20

Ecologists sometimes use ________ as simpler representations of the complex natural world.

A) character displacement
B) mathematical or laboratory models
C) competition coefficients
D) replication
E) None of the choices are correct.

Question 21

Intraspecific competition for limited resources can play a key role in slowing population growth at high densities.

Question 22

An invasive species, Batallaria attramentaria, has been shown to grow faster than native species and both small and medium snail densities.

Question 23

Rodents that feed primarily on seeds are called ________.

Question 24

Research by James Byers on the relationship between a native and an invasive species of mud snail

A) demonstrated that the invasive species Batillaria grows faster than the native species Cerithidea.
B) demonstrated that at high densities Batillaria continued to grow at a relatively high rate while Cerithidea lost weight.
C) indicated that Batillaria is much more efficient at converting available food into its own biomass.
D) predicts a time to competitive exclusion of Cerithidea by Batillaria of 55 to 70 years.
E) All of the choices are correct.

Question 25

Geospiza fortis, medium ground finch, and Geospiza fulginosa, small ground finch, have similar beak sizes when they do not live together. However, when they live together the beaks sizes are different. This is an example of

A) character displacement
B) mutualism
C) commensalism
D) intraspecific competition

Question 26

Pachypsylla cohabitans, a psyllid (jumping plant lice), feeds next to other gall-forming psyllids in order to be enveloped in the gall. This doesn't harm the gall-forming insect. This relationship is an example of

A) mutualism.
B) amensalism.
C) parasitism.
D) commensalism.

Question 27

Amensalism is rare in nature because

A) interactions between species typically benefit both species.
B) most species have a neutral affect on each other.
C) no affect on one species cancels out any negative affect to the other.
D) there is usually an energetic cost to interactions between two species.

Question 28

Damselfish will fight over newly available territory. This is a direct interaction between individuals and is an example of

A) interference competition.
B) mutualism.
C) commensalism.
D) predation.

Question 29

In the Lotka-Volterra competition model, the intersection of two isoclines of zero population growth always indicates stable coexistence of two competitors.

Question 30

Experiments with terrestrial isopods demonstrate that competition can occur only when food resources are limiting.

Question 31

The process of evolution toward niche divergence in the face of competition is called ________.

A) niche displacement
B) niche evolution
C) character displacement
D) character evolution
E) allopatric displacement

Question 32

Evolution of distinct niches in the presence of competition is called ________.

Question 33

Within a species, all individuals have identical niches.